Thursday, July 1, 2010

Get Growing in July


Insects are our friends

July brings the summer harvests to New England. During this month we will be inundated with zucchini, cucumbers, and beans, but unless you planted early tomatoes the first tomato won't hit until the end of July or early August. And though I have no corn in my garden this year, I'm sure I'll be buying a lot of it from the farmers markets this month.

These flowers were female

If you look close at your zucchini plants you will notice that there are two types of flowers. There are male blossoms that have normal stems behind the flower and female blossoms that have little tiny zucchinis behind the flower. All cucurbits (cucumbers, melons, squash, pumpkins, gourds) are like this. Many other plants can self pollinate their flowers (like tomatoes, beans, peas, and peppers), but cucurbits can't. They require bees to pollinate. If you notice that your female blossoms have opened and then a few days later they fall off and die, it is most likely because the flowers weren't pollinated. You can hand pollinate by transferring the pollen from the male blossoms to the female blossom, but it is so much easier if the bees are doing their job.

This is one reason I never spray a broad spectrum pesticide on my plants. I have several approaches to insect control to avoid it. The first approach is to let nature take it course. In the spring I do get some aphids. In not long the lady bugs and lacewings come in to take care of them. I find that nature controls these kinds of insects fairly well in my garden. But I do help her out. I plant perennial flowers around the vegetable garden to encourage the beneficial insects. Mallow is a great plant to attract bees, as is bee balm, and even some varieties of coreopsis. Marigolds attract hoverflies which is a predatory insect. Also I let my umbelliferae family herbs (cilantro/coriander, parsley, and dill) bloom every year. Adult lacewings and the predatory wasps love these blooms. In addition the plants will self seed every year and you can harvest the coriander and dill seed for your spice rack.

Lacewing eggs on dill are tiny, but grow into voracious aphid eaters

The above is an example of companion planting. But companion planting can do more than attract the good insects. It can also attract the bad. For instance if you plant borage. It will attract bees to the garden, but it will also attract aphids. You might think this is a bad thing, but it is called a trap crop. If the aphids like the borage more than they like your peas then your peas will have less aphids. It will also give the aphids a place to live in an innocuous place. A lady bug won't lay eggs in your garden if there are no aphids around. But better on the borage than on your peas. Nasturtiums are another good trap crop. I've heard many insects that they attract from caterpillars to flee beetles. Personally I've only noticed they they attract aphids.

A companion plant can also repel insects. It isn't uncommon for people to scatter onions throughout the carrot patch. The scent of the onions helps to repel the carrot fly. One of my favorite plants in this category is the marigold. I always plant my tomatoes near them. Marigolds are toxic to the root knot nematode. These nematodes can seriously stunt crops.

Ground Control Marigolds

So you plant companions. You have some that attract and some that repel, but you still have an insect problem. Your plants are getting eaten. I have four other strategies that don't require any pesticides. I can hand pick them. Big insects are particularly easy. I get a bowl of soapy water and knock the insect into it. I know gardeners that squish the bugs with their hands, but I'm a bit too squeamish for that. If aphids get really out of hand I cut off the infested part (usually just one branch) and toss it into the lawn near the garden. I don't know if it helps, but I figure if the lady bugs find the aphids there it is just as good.

The second way is to trap your insects. Not all insects have good traps, but some do. The only insect trap in the garden I use is a flee beetle trap. It is very simple to make. Have a white bowl filled with soapy water. Leave it out under the plant. If it rains a lot replenish it. It might not kill all the flee beetles, but I find it will keep the numbers way down so they aren't seriously damaging the plants. I occasionally use it for the tomato family crops, but I use it every year with the Asian greens.

The third is a row cover. This is a light cloth, usually remay in the US. You put on right after the plants are put in the ground. It has to be on the plants their whole life, or the bad bugs will breed under it without any predators. Often it is held up off the plants with supports. The trick is that you have to tack the edges down well to keep the insects from finding a way in. Its biggest flaw is that it raises the air temperature. If you are growing in the summer, make sure you get the lightest one available. I use these on my brassicas because I've found them almost impossible to grow without one. Between flee beetles, root maggots, and caterpillars, it is just easier to throw on a row cover.

The fourth strategy I've only used on one crop. Squash. My insect nemesis is the squash vine borer. It is a moth that looks a little like a red and black wasp. The female lays her eggs all along the stem of the squash vine. She can lay up to a hundred of the eggs. When the egg hatches the caterpillar tunnels into the vine and destroys it from the inside. The first sign of damage you notice is that your vine is wilting even in the mornings when it has been watered (vines will often wilt in the hot afternoon sun even without borers). I've tried picking off the eggs. I always miss some. I've tried slitting along the stem to get out the borer. The plant is unhappy. I can't use a row cover because the flowers need to be pollinated. There aren't a lot of solutions. So I plant resistant varieties of squash. There is one species, C. moschata, that is resistant. Sadly pumpkins are C. pepo, but butternut squash is in the C. moschata species so that is what I grow. Zucchini is C. pepo too, but the borer won't kill the plant until sometime in August and by that time I'm pretty sick of zucchini anyway. Winter squash on the other hand takes a long time to mature so mine are resistant.

When all else fails people go to pesticides. I'm not a big fan. I don't like things that are broad spectrum since they kill the the good insects with the bad. If you feel you must, please spray in the early, early morning before the bees become active or at night when they are in their hive. There are a handful of insecticides that I have used in the garden at times. Bt is Bacillus Thuringiensis. It often goes under the brand name Dipel. It is a bacteria that is specific to caterpillars (some strains are used for other larvea). It will not hurt any other insect in the garden. If you are not using a row cover on your brassicas, I would heartily recommend using it as a caterpillar control. Don't spray it willy nilly about the garden though. It kills all caterpillars including the "good" ones. Black swallowtails will lay eggs on dill, fennel, parsley, and sometimes carrots. I love the butterflies so am happy to lose a couple of plants to them. The smile on my face when I see them is more than enough to pay for the loss of some dill. So if you like to see butterflies around, keep the Bt in your brassicas and away from the other plants.


Another targeted pesticide that I've come to enjoy is Sluggo. It is Iron Phosphate, which is pretty non toxic. Slugs are a huge problem in my rainy New England garden. Some years I hand pick to control them, but you have to do this about every other night (yes I said night as they are nocturnal creatures) and sometimes even that is not enough to keep the plants alive. I'm not fond of fighting mosquitoes to get to the slugs either. Sluggo does a pretty good job of control. So I use it.

I've used two other pesticides over the years. I've used Diatomaceous Earth. This is the fossil remains diatoms. They are very sharp (and shouldn't be breathed), but so tiny you won't notice it. The slugs however get lacerated by the little knives. The flaw with this control is that it is only effective when dry and slugs are most active when we get a lot of rain. You have to reapply constantly to keep it working right. It is also not specific. It can kill chitinous insects too including the rove beetle, which is a slug predator.

The last is just insecticidal soap. I used to use this before my garden had a good balance of the good insects to bad. Now I just wait for the predators to show up whenever I have an aphid infestation. They never fail me.

Planting the Fall Crops

In last month's segment we talked about starting the longer mature fall crops. Well mid to late July is the time to plant most of them. If we are getting very hot weather you might have to pamper them a little bit. Make sure they get plenty of water. You can also start some more transplants this month. This time start the earlier maturing Asian greens, like bok choy for transplanting in August. You can just direct seed, but often July is too hot for them outside and slugs are rampant in the garden. An Asian green seedling doesn't have much of a chance.

You can however direct seed carrots. If you want full sized fall carrots plant them by mid July. Make sure you keep them well watered or they won't come up in the heat. A board over the row is very useful for shade and to keep in moisture. Check under the board every day and if you see them start to sprout remove it.

Other post in the series

Planning a Garden (Daphne's Dandelions - December)
Growing Lettuce (Vegetable Matter - January)
Starting transplants indoors (Daphne's Dandelions - January)
Growing tomatoes (Vegetable Matter - February)
Compost (Daphne's Dandelions - February)
Snap Beans (Vegetable Matter - March)
Peas and Spinach (Daphne's Dandelions - March)
Eggplant (Vegetable Matter - April)
Edamame (Vegetable Matter - May)
Tomatoes (Daphne's Dandelions - May)
Lima Beans (Vegetable Matter - June)
Disease Control (Daphne's Dandelions - June)


  1. You are providing such a great series of informative posts. While I am not a newbie gardener, I very much enjoy reading these every month as they are a great overview and a nice review.

  2. Daphne... you are so awesome to share you gardening knowledge with us!!!

  3. Insects are a hard one to give info for everyone. Usually you need specific information about controlling a particular insect. So mostly I've done the strategies for control and each person will have to look up control for the insect they need help with. I've been reading Jane's posts about growing crops in Hawaii and some of her insects I've never even heard of before.

  4. Thanks for the tips. Right now the slugs and aphids are my biggest headaches!!

  5. WOW! Mahalo for your great post on insect control - such excellent information!

  6. Thanks for the refresher. As a master gardener, I know all of this stuff but it is nice to be reminded. I also have taken the "it all balances out in the end" approach.

  7. I've just stumbled upon this series - thanks so much. I headed over to Vegetable Matter too as she is the same zone as I am.

  8. Another great GG post. Excellent info !

  9. Toni, thanks

    Holly, I so hate slugs, but this year is so much easier than last year.

    A Kitchen Garden in Kihei Maui, thanks

    johanna, it took a while for my garden to balance out. At the start there weren't a lot of good insects around.

    Miss M, thanks

  10. Another great slug repellent that works for me is sand, I used it last year around the base of plants. I guess they don't like to cross it as it tears up their bellies. Cheap and easy :)